modelEvaporatorCondenser
Evaporator or condenser with refrigerant experiencing constant temperature phase change
Extends from Buildings.Fluid.Interfaces.TwoPortHeatMassExchanger.
Information
Model for a constant temperature evaporator or condenser based on a ε-NTU heat exchanger model.
The heat exchanger effectiveness is calculated from the number of transfer units (NTU):
ε = 1 - exp(- UA ⁄ (ṁ cp))
Optionally, this model can have a flow resistance.
If no flow resistance is requested, set dp_nominal=0.
Limitations
This model does not consider any superheating or supercooling on the refrigerant side. The refrigerant is considered to exchange heat at a constant temperature throughout the heat exchanger.
Parameters
| Type | Name | Default | Description |
|---|---|---|---|
| Modelica.Units.SI.ThermalConductance | UA | Thermal conductance of heat exchanger | |
| Advanced | |||
| Modelica.Units.SI.ThermalConductance | UA_small | UA/10 | Small thermal conductance for regularisation of heat transfer |
Components
| Type | Name | Default | Description |
|---|---|---|---|
| Modelica.Blocks.Interfaces.RealOutput | Q_flow | Heat added to the fluid | |
| Modelica.Blocks.Interfaces.RealOutput | T | Medium temperature | |
| Modelica.Thermal.HeatTransfer.Interfaces.HeatPort_a | port_ref | Temperature and heat flow from the refrigerant | |
| Modelica.Units.SI.Efficiency | NTU | UA/(Buildings.Utilities.Math.Functions.smoothMax(abs(port_a.m_flow), m_flow_small, m_flow_small)*cp_default) | Number of transfer units of heat exchanger |
| Modelica.Units.SI.Efficiency | eps | Buildings.Utilities.Math.Functions.smoothMin(Buildings.Fluid.HeatExchangers.BaseClasses.epsilon_ntuZ(NTU, 0, Integer(Buildings.Fluid.Types.HeatExchangerFlowRegime.ConstantTemperaturePhaseChange)), 0.999, 1.0e-4) | Effectiveness of heat exchanger |
| Modelica.Blocks.Sources.RealExpression | UAeff | Effective heat transfer coefficient |
Revisions
-
March 7, 2022, by Michael Wetter:
RemovedmassDynamics.
This is for #1542. -
May 27, 2017, by Filip Jorissen:
Regularised heat transfer around zero flow.
This is for #769. -
April 12, 2017, by Michael Wetter:
Corrected invalid syntax for computing the specific heat capacity.
This is for #707. -
October 11, 2016, by Massimo Cimmino:
First implementation.